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排序方式： 共有107条查询结果，搜索用时 0 毫秒
1.
In the study, a series of C_(30)-C_(32) lanostane homologs have been identified from Eogene source rocks and crude oils of Biyang depression in Henan Province, China. Based upon the geochemical investigations and simulating experiments, the idea that the generation of lanostane may mainly be related to the specific original organic inputs and low maturity has been proposed. 相似文献
2.
李任伟 《中国科学B辑(英文版)》1990,(3)
Not only the mudstones and carbonates deposited in hypersaline environments, but also evaporites can be source rocks of petroleum. They all have a peculiar composition of hydrocarbon such as the strong predominance of phytane, the richness in gammacerane, the frequent preference of even carbon number n-alkanes, and have a generative potential for less mature oils in diagenesis of organic matter. 相似文献
3.
Haifeng Xu Mariana Medina-Sánchez Oliver G. Schmidt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15139-15147
An integrated system combining a magnetically-driven micromotor and a synthetized protein-based hyaluronic acid (HA) microflake is presented for the in situ selection and transport of multiple motile sperm cells (ca. 50). The system appeals for targeted sperm delivery in the reproductive system to assist fertilization or to deliver drugs. The binding mechanism between the HA microflake and sperm relies on the interactions between HA and the corresponding sperm HA receptors. Once sperm are captured within the HA microflake, the assembly is trapped and transported by a magnetically-driven helical microcarrier. The trapping of the sperm-microflake occurs by a local vortex induced by the microcarrier during rotation-translation under a rotating magnetic field. After transport, the microflake is enzymatically hydrolyzed by local proteases, allowing sperm to escape and finally reach the target location. This cargo-delivery system represents a new concept to transport not only multiple motile sperm but also other actively moving biological cargoes. 相似文献
4.
不同基质生态条件对葡萄硬枝扦插的催根效应 总被引：3，自引：0，他引：3
锯末、素砂、砂壤等3种基质对葡萄硬枝扦插的催根效应是不同的锯末、素砂对插条的催根数分别比砂壤增加27％和23．9％,根的长度分别比砂壤增加34．8％和3．g％;根的粗度锯末比砂壤增加7．8％,素砂比砂壤减少9．5％;3种基质催根成活率分别为104)％,97％,94％锯末的保温性、相对含水量、通气性均优于素砂和砂壤,有利于葡萄硬技扦插催根。 相似文献
5.
分别以日本结缕草的成熟胚和茎节为外植体,建立并优化了2套组培再生体系.实验结果表明:利用成熟胚诱导愈伤组织,适宜诱导培养基为MS基本培养基添加2 mg/L 2,4-D配合0.2 mg/L 6-BA,诱导率为42.5%;继代培养可改善愈伤组织状态,增加胚性,其中增加培养基渗透压,并适当添加ABA(0.2 mg/L),可明显提高胚性愈伤组织比率;继代2次后的愈伤组织在3种细胞分裂素6-BA,KT,ZT适当配比的分化培养基上,分化率可达到50%~75%.在以茎节为外植体的组培体系中消毒处理和预培养是比较关键的环节;预培养时MS培养基效果优于1/2 MS,在MS基本培养基中添加0.25 mg/L KT,1.0 mg/L ZT和0.1 mg/L NAA为比较适合的芽诱导培养基,诱导率可达37.9%.同时,比较了两套再生体系的优缺点,为日后日本结缕草的遗传转化奠定基础. 相似文献
6.
韩笑 《达县师范高等专科学校学报》2011,(4):93-96
浪漫主义是18世纪末19世纪初欧洲普遍流行的一种文艺思潮。浪漫主义批评追求自由,强调个性解放与情感至上,它以充满激情的夸张方式来表达理想与愿望。通过对浪漫主义批评理论发展的回顾,分析了浪漫主义批评理论的贡献与缺陷,从而尽可能地使浪漫主义批评理论得以充分展现。 相似文献
7.
Ilektra Sperdouli Julietta Moustaka Georgia Ouzounidou Michael Moustakas 《Molecules (Basel, Switzerland)》2021,26(14)
We investigated flavonoid accumulation and lipid peroxidation in young leaves (YL) and mature leaves (ML) of Arabidopsis thaliana plants, whose watering stopped 24 h before sampling, characterized as onset of drought stress (OnDS), six days before sampling, characterized as mild drought stress (MiDS), and ten days before sampling, characterized as moderate drought stress (MoDS). The response to drought stress (DS) of photosystem II (PSII) photochemistry, in both leaf types, was evaluated by estimating the allocation of absorbed light to photochemistry (ΦPSII), to heat dissipation by regulated non-photochemical energy loss (ΦNPQ) and to non-regulated energy dissipated in PSII (ΦNO). Young leaves were better protected at MoDS than ML leaves, by having higher concentration of flavonoids that promote acclimation of YL PSII photochemistry to MoDS, showing lower lipid peroxidation and excitation pressure (1 − qp). Young leaves at MoDS possessed lower 1 − qp values and lower excess excitation energy (EXC), not only compared to MoDS ML, but even to MiDS YL. They also possessed a higher capacity to maintain low ΦNO, suggesting a lower singlet oxygen (1O2) generation. Our results highlight that leaves of different developmental stage may display different responses to DS, due to differential accumulation of metabolites, and imply that PSII photochemistry in Arabidopsis thaliana may not show a dose dependent DS response. 相似文献
8.
石蜡切片技术是一项基础的实验技术,在具体操作过程中仍经常在的裂纹、皱缩、不粘片、脱落、薄厚不匀等问题.且不同作物,同一种作物不同器官,同一器官不同发育阶段,每一环节所采取的方法不同,在实际操作工程中均不能照搬实验指导或者文献,而需要进行反复摸索才可以制得一个理想的片子.实验以小茴香成熟叶柄为材料,通过大量的摸索性试验,成功制得了小茴香成熟叶柄的永久性石蜡片子,明确了叶柄的内部组织构造,提出了取材与固定、脱水与透明、浸蜡与包埋、染色、切片、粘片等关键环节的适宜操作方法,提高了制片效率和成功率,为利用石蜡切片技术进行科研和教学的工作人员提供参考. 相似文献
9.
基因型及生长调节物质对玉米成熟胚培养的影响 总被引：2，自引：0，他引：2
对30个基因型的玉米成熟胚进行离体培养,研究不同基因型对培养的反应和培养基对成熟胚愈伤组织诱导和生长的影响.结果表明,成熟胚的愈伤可诱导能力较为普遍,但诱导频率因基因型的不同有很大差异,不同基因型所诱导出的愈伤质量也有所不同;MS、N6两种基本培养基对成熟胚出愈率的高低影响不大;不同的生长调节物质对成熟胚愈伤组织生长状况有明显的影响,脯氨酸的添加对愈伤组织质量有促进作用;细胞分裂素对愈伤组织的质量和长势均有一定的负面影响. 相似文献
10.